Phytochemical profiles and antioxidant activity of brown rice varieties

- Phenolic acids and flavonoids were identified and quantified in brown rice.
- Flavonoids were major compounds responsible for antioxidant capacity in free form.
- Phenolic acids were major compounds responsible for antioxidant capacity in bound form.

The phytochemical content and antioxidant activity of eight varieties of brown rice (BR) are reported. The total phenolic contents of BR ranged from 72.45 to 120.13 mg of gallic acid equiv./100 g. The phenolics from bound fraction contributed 40.6-50.2% of the total phenolic content. The total flavonoid contents of BR ranged from 75.90 to 112.03 mg catechin equiv./100 g. The flavonoids from the bound fraction contributed 26.9-48.2% of total flavonoids. Trans-ferulic acid was the predominant phenolic acid in BR. Total trans-ferulic acid content ranged from 161.42 to 374.81 μg/100 g. The percentage of trans-ferulic acid in bound fraction ranged from 96.4% to 99.2%. Only α- and γ-tocopherols and -tocotrienols were detected in BR with α-tocopherol and γ-tocotrienol being the predominant. The total peroxyl radical scavenging capacity (PSC) of BR ranged from 18.29 to 40.33 mg vitamin C equiv./100 g. The bound fraction contributed 67.2-77.2% of total PSC.